The objective of the current study was to investigate the effect of palm kernel meal (PKM) and Aspergillus wentii TISTR 3075 fermented PKM at various levels on growth performance and nutrient digestibility of broiler chickens. Four hundred and thirty-two day old Ross-308 broiler chicks were used in a 2 × 4 factorial in completely randomized design with one control. Two kinds of PKM (unfermented and A. wentii fermented PKM) in broiler rations were used, each at 10, 20, 30 and 40 %. Increasing level of PKM or A. wentii fermented PKM higher than 20 % significantly decreased feed intake and average weight gain also decreased, while feed efficiency declined. Feed intake of growing broilers during 0 to 21 d of age fed with PKM decreased linearly followed by a quadratic response during the finishing period (22 to 42 d of age) while those broilers fed with A. wentii fermented PKM exhibited a quadratic response throughout the 42 d feeding trial. Data show that feed intake and average weight gain response when fed with PKM decreased linearly while when fed with A. wentii fermented PKM it was quadratic and then slowly decreased. The poor performance of the birds fed PKM or A. wentii fermented PKM at high levels might be due to the higher in crude fiber content and the lower nitrogen retention. In the growing period PKM or A. wentii fermented PKM no more than 20 % of the broiler ration should be used while in the finishing period PKM up to 30 % is effective. Walailak J Sci & Tech 2013; 10(2) 131-147